WO2019167508A1

WO2019167508A1 - Lock-up control device and control method for automatic transmission

Info

Publication number: WO2019167508A1
Application number: PCT/JP2019/002622
Authority: WO
Inventors: 直泰池田; 旭明王
Original assignee: ジヤトコ株式会社; 日産自動車株式会社
Priority date: 2018-02-27
Filing date: 2019-01-28
Publication date: 2019-09-06
Also published as: JP6942238B2; JPWO2019167508A1

Abstract

A belt-type continuously variable transmission (CVT) is provided with a torque converter (2), a lock-up clutch (20), and a CVT control unit (8). A lock-up control unit (80) calculates a converter torque (Tcnv) through feed forward compensation based on a target differential rotation speed (ΔN^*) and feedback compensation based on differential rotation speed deviation (δ), obtains a target LU torque (Tlu^*) by subtracting the converter torque (Tcnv) from an adjusted engine torque (Tadj) inputted to the torque converter (2), and outputs the corresponding indicated current (Alu). When a start condition for coasting slip control is satisfied during coasting based on an acceleration release operation, the control unit (80) resets the converter torque F/B compensation amount to an initial value, and starts the coasting slip control.

Description

Lockup control device and control method for automatic transmission

The present invention relates to a lockup control device and control method for an automatic transmission mounted on a vehicle.

2. Description of the Related Art Conventionally, a lockup control device for an automatic transmission that performs coast capacity learning control while acquiring an initial value of a lockup differential pressure by learning control during coasting (= during coasting) is known (for example, Patent Documents). 1).

The conventional apparatus has a problem that it is necessary to experience learning control repeatedly until a desired learning value can be acquired as the initial value of the lockup differential pressure. Also, since the initial value of the lock-up differential pressure by learning control is used at the start of coast capacity learning control, the initial differential pressure varies depending on the operating state before the coast capacity learning control starts, and in the start area of coast capacity learning control. There was a problem that the slip amount fluctuated.

The present invention has been made paying attention to the above problem, and it is an object of the present invention to maintain stable slip rotation immediately after the start of coast slip control without the need for learning control during coasting.

JP-A-9-203462

The present invention includes a torque converter, a lock-up clutch, and a transmission controller.
The transmission controller calculates the converter torque by feedforward compensation based on the target differential speed and feedback compensation based on the differential speed deviation, and the target lockup torque calculated by subtracting the converter torque from the input torque to the torque converter. There is provided a lock-up control unit for executing the obtained slip control.
The lockup control unit resets the converter torque feedback compensation amount in the feedback compensation to the initial value and starts the coast slip control when the start condition of the coast slip control is satisfied during the coast running by the accelerator release operation.

In this way, by starting the coast slip control by resetting the initial value for the converter torque feedback compensation, it is possible to maintain a stable slip rotation immediately after the start of the coast slip control without the need to perform the learning control during the coast running. it can.

1 is an overall system diagram showing a drive system and a control system of an engine vehicle to which a lockup control device for an automatic transmission according to an embodiment is applied. It is a shift schedule figure which shows an example of the D range continuously variable transmission schedule used when the continuously variable transmission control in automatic transmission mode is performed by a variator. It is a schematic block diagram which shows the lockup control apparatus of an Example. It is a block block diagram which shows each block which comprises the lockup control part of a CVT control unit. It is a detailed block diagram which shows the target calculation block, torque capacity calculation block, and realization block which comprise a lockup control part. It is a flowchart which shows the flow of the coast slip control process performed in the lockup control part of the CVT control unit of an Example. It is a flowchart which shows the flow of the lockup clutch torque capacity control processing performed in the lockup control part of the CVT control unit of an Example. Accelerator opening APO, LU requirement, idle switch Idle SW, fuel cut flag F / C flag, learning conditions, engine torque Te, turbine speed Nt, engine in coast capacity learning control executed during coast running in comparative example 4 is a time chart showing characteristics of a rotational speed Ne / LU indicated differential pressure. It is a flowchart which shows the flow of examination operation | movement at the time of examining whether coast capacity learning control in a comparative example can be replaced by coast slip control. Accelerator opening APO, target differential rotation, idle switch Idle SW, fuel cut flag F / C flag, coast slip request, LU torque, LU command differential pressure, turbine in coast slip control executed during coast running in the embodiment 5 is a time chart showing characteristics of a rotational speed Nt and an engine rotational speed Ne.

Hereinafter, a mode for carrying out a lockup control device for an automatic transmission according to the present invention will be described based on an embodiment shown in the drawings.

The lockup control device in the embodiment is applied to an engine vehicle equipped with a belt-type continuously variable transmission (an example of an automatic transmission) configured by a torque converter, a forward / reverse switching mechanism, a variator, and a final reduction mechanism. . Hereinafter, the configuration of the embodiment is divided into “the overall system configuration”, “the configuration of the lockup control device”, “the detailed configuration such as the torque capacity calculation block”, “the coast slip control processing configuration”, “the lockup clutch torque capacity control processing”. The description will be divided into “configuration”.

[Overall system configuration]
FIG. 1 shows a drive system and a control system of an engine vehicle to which a lockup control device for an automatic transmission according to an embodiment is applied. The overall system configuration will be described below with reference to FIG.

As shown in FIG. 1, the drive system of the engine vehicle includes an engine 1, a torque converter 2, a forward / reverse switching mechanism 3, a variator 4, a final reduction mechanism 5, and

drive wheels

6 and 6. Yes. Here, the belt type continuously variable transmission CVT is configured by incorporating the torque converter 2, the forward / reverse switching mechanism 3, the variator 4, and the final reduction mechanism 5 in a transmission case (not shown).

The engine 1 can control the output torque by an engine control signal from the outside, in addition to the output torque control by the accelerator operation by the driver. The engine 1 includes an output torque control actuator 10 that performs torque control by a throttle valve opening / closing operation, a fuel cut operation, and the like. For example, fuel cut control is executed during coasting by an accelerator release operation.

The torque converter 2 is a starting element by a fluid coupling having a torque increasing function and a torque fluctuation absorbing function. The torque converter 2 has a lock-up clutch 20 that can directly connect the engine output shaft 11 (= torque converter input shaft) and the torque converter output shaft 21 when a torque increasing function and a torque fluctuation absorbing function are not required. The torque converter 2 includes a pump impeller 23, a turbine runner 24, and a stator 26 as constituent elements. The pump impeller 23 is connected to the engine output shaft 11 via the converter housing 22. The turbine runner 24 is connected to the torque converter output shaft 21. The stator 26 is provided in the transmission case via the one-way clutch 25.

The forward / reverse switching mechanism 3 is a mechanism that switches the input rotation direction to the variator 4 between a forward rotation direction during forward travel and a reverse rotation direction during reverse travel. The forward / reverse switching mechanism 3 includes a double pinion planetary gear 30, a forward clutch 31 using a plurality of clutch plates, and a reverse brake 32 using a plurality of brake plates. The forward clutch 31 is hydraulically engaged by the forward clutch pressure Pfc when a forward travel range such as the D range is selected. The reverse brake 32 is hydraulically engaged by the reverse brake pressure Prb when the reverse travel range such as the R range is selected. The forward clutch 31 and the reverse brake 32 are both released by draining the forward clutch pressure Pfc and the reverse brake pressure Prb when the N range (neutral range) is selected.

The variator 4 has a primary pulley 42, a secondary pulley 43, and a pulley belt 44, and continuously changes the transmission gear ratio (ratio of variator input rotation to variator output rotation) by changing the belt contact diameter. A gear shifting function is provided. The primary pulley 42 includes a fixed pulley 42 a and a slide pulley 42 b arranged on the same axis as the variator input shaft 40, and the slide pulley 42 b is slid by the primary pressure Ppri guided to the primary pressure chamber 45. The secondary pulley 43 includes a fixed pulley 43 a and a slide pulley 43 b arranged on the same axis as the variator output shaft 41, and the slide pulley 43 b is slid by the secondary pressure Psec guided to the secondary pressure chamber 46. The pulley belt 44 is stretched around a sheave surface that forms a V shape of the primary pulley 42 and a sheave surface that forms a V shape of the secondary pulley 43. The pulley belt 44 is formed of two sets of laminated rings in which a large number of annular rings are stacked from the inside to the outside and a plurality of punched plate members, and is attached by being laminated in an annular manner by being sandwiched along the two sets of laminated rings. It is composed of elements. The pulley belt 44 may be a chain-type belt in which a large number of chain elements arranged in the pulley traveling direction are coupled by pins penetrating in the pulley axial direction.

The final deceleration mechanism 5 is a mechanism that decelerates the variator output rotation from the variator output shaft 41 and transmits it to the left and

right drive wheels

6 and 6 while providing a differential function. The final speed reduction mechanism 5 is a speed reduction gear mechanism that includes an output gear 52 provided on the variator output shaft 41, an idler gear 53 and a reduction gear 54 provided on the idler shaft 50, and a final gear provided on the outer peripheral position of the differential case. And a gear 55. The differential gear mechanism includes a differential gear 56 interposed between the left and

right drive shafts

51, 51.

As shown in FIG. 1, the engine vehicle control system includes a hydraulic control unit 7, a CVT control unit 8, and an engine control unit 9. The CVT control unit 8 and the engine control unit 9 which are electronic control systems are connected by a CAN communication line 13 which can exchange information with each other.

The hydraulic control unit 7 performs primary pressure Ppri guided to the primary pressure chamber 45, secondary pressure Psec guided to the secondary pressure chamber 46, forward clutch pressure Pfc to the forward clutch 31, reverse brake pressure Prb to the reverse brake 32, and the like. It is a unit that regulates pressure. The hydraulic control unit 7 includes an oil pump 70 that is rotationally driven by the engine 1 that is a travel drive source, and a hydraulic control circuit 71 that adjusts various control pressures based on the discharge pressure from the oil pump 70. . The hydraulic control circuit 71 includes a line pressure solenoid valve 72, a primary pressure solenoid valve 73, a secondary pressure solenoid valve 74, a select solenoid valve 75, and a lockup pressure solenoid valve 76. Each

solenoid valve

72, 73, 74, 75, 76 performs a pressure adjustment operation according to a control command value (indicated current) output from the CVT control unit 8.

The line pressure solenoid valve 72 adjusts the discharge pressure from the oil pump 70 to the commanded line pressure PL according to the line pressure command value output from the CVT control unit 8. The line pressure PL is a source pressure when adjusting various control pressures, and is a hydraulic pressure that suppresses belt slip and clutch slip against torque transmitted through the drive system.

The primary pressure solenoid valve 73 adjusts the pressure to the primary pressure Ppri commanded using the line pressure PL as the original pressure in accordance with the primary pressure command value output from the CVT control unit 8. The secondary pressure solenoid valve 74 adjusts the pressure to the secondary pressure Psec commanded using the line pressure PL as the original pressure in accordance with the secondary pressure command value output from the CVT control unit 8.

The select solenoid valve 75 adjusts the pressure to the forward clutch pressure Pfc or the reverse brake pressure Prb commanded using the line pressure PL as the original pressure according to the forward clutch pressure command value or the reverse brake pressure command value output from the CVT control unit 8. To do.

The lock-up pressure solenoid valve 76 adjusts to a lock-up hydraulic pressure Plu for engaging / slipping / releasing the lock-up clutch 20 according to the command current Alu output from the CVT control unit 8.

The CVT control unit 8 performs line pressure control, shift control, forward / reverse switching control, lockup control, and the like. In the line pressure control, a command value for obtaining a target line pressure corresponding to the accelerator opening is output to the line pressure solenoid valve 72. In the shift control, when the target gear ratio (target primary rotation Npri ^* ) is determined, a command value for obtaining the determined target gear ratio (target primary rotation Npri ^* ) is output to the primary pressure solenoid valve 73 and the secondary pressure solenoid valve 74. In the forward / reverse switching control, a command value for controlling the engagement / release of the forward clutch 31 and the reverse brake 32 is output to the select solenoid valve 75 according to the selected range position. In the lockup control, the command current Alu for controlling the lockup hydraulic pressure Plu for engaging / slipping / releasing the lockup clutch 20 is output to the lockup pressure solenoid valve 76.

The CVT control unit 8 includes a primary rotation sensor 90, a vehicle speed sensor 91, a secondary pressure sensor 92, an oil temperature sensor 93, an inhibitor switch 94, a brake switch 95, a turbine rotation sensor 96, a secondary rotation sensor 97, a primary pressure sensor 98, and the like. Sensor information and switch information are input.

The engine control unit 9 receives sensor information from the engine rotation sensor 12, accelerator opening sensor 14, and the like. When the CVT control unit 8 requests the engine control information and the accelerator opening information to the engine control unit 9, the CVT control unit 8 receives information on the engine speed Ne and the accelerator opening APO via the CAN communication line 13. Further, when requesting engine torque information to the engine control unit 9, information on the actual engine torque Te estimated in the engine control unit 9 is received via the CAN communication line 13.

FIG. 2 shows an example of the D range continuously variable transmission schedule used when the variator 4 executes the continuously variable transmission control in the automatic transmission mode when the D range is selected.

The “D range shift mode” is an automatic shift mode in which the gear ratio is automatically changed steplessly in accordance with the vehicle operating state. The shift control in the “D range shift mode” is performed by operating points on the D range continuously variable shift schedule of FIG. 2 specified by the vehicle speed VSP (vehicle speed sensor 91) and the accelerator opening APO (accelerator opening sensor 14) ( VSP, APO) determines the target primary rotational speed Npri ^* . Then, the pulley primary pressure control is performed so that the actual primary rotational speed Npri from the primary rotational sensor 90 matches the target primary rotational speed Npri ^* .

That is, as shown in FIG. 2, the D range continuously variable transmission schedule used in the “D range speed change mode” has a gear ratio range of the lowest gear ratio and the highest gear ratio according to the operating point (VSP, APO). Within the range, the gear ratio is set to change steplessly. For example, when the vehicle speed VSP is constant, and shifting the downshift direction to perform the increased target primary rotation speed Npri ^* the accelerator depression operation, the target primary rotation speed Npri ^* decreases Doing accelerator return operation up Shift in the shift direction. When the accelerator opening APO is constant, the vehicle shifts in the upshift direction when the vehicle speed VSP increases, and the vehicle shifts in the downshift direction when the vehicle speed VSP decreases.

[Configuration of lock-up control device]
FIG. 3 shows the lock-up control device of the embodiment. Hereinafter, a schematic configuration of the lockup control device will be described with reference to FIG. In the following, lockup is abbreviated as “LU”, feedforward is abbreviated as “F / F”, and feedback is abbreviated as “F / B”.

As shown in FIG. 3, the drive system to which the lockup control device is applied includes an engine 1 (driving drive source), a torque converter 2 having a lockup clutch 20, a forward / reverse switching mechanism 3, and a variator 4. The final reduction mechanism 5 and the drive wheels 6 are provided.

As shown in FIG. 3, the control system to which the lockup control device is applied includes a CVT control unit 8, an engine control unit 9, and a lockup pressure solenoid valve 76. The CVT control unit 8 is provided with a lockup control unit 80 that changes the clutch state of the lockup clutch 20 to the engaged state / slip engaged state / released state according to various requests.

The lockup control in the lockup control unit 80 estimates the target driving force Fd ^* intended by the driver, and locks up the clutch so that the actual driving force Fd output to the driving wheels 6 becomes the target driving force Fd ^*. 20 slip control is performed. At this time, the target driving force Fd ^* is converted into the target engine speed Ne ^* in order to improve the controllability in the slip control. The converter torque Tcnv is calculated by executing control (F / F control + F / B control) for converging the actual engine speed Ne to the target engine speed Ne ^* . Then, as shown in FIG. 3, Tadj = Tcnv + Tlu relationship that holds, calculates a target LU torque TLU of the lockup clutch 20 ^*, the target LU torque TLU ^* the obtained command current Alu lockup pressure solenoid valve 76 Output to. In this way, by controlling the torque ratio of the torque converter 2 so as to obtain the target engine speed Ne ^* , the target driving force Fd ^* intended by the driver can be realized during the slip control of the lockup clutch 20. Can do.

FIG. 4 shows each block constituting the lockup control unit 80 of the CVT control unit 8. Hereinafter, the block configuration of the lockup control unit 80 will be described with reference to FIG.

The lockup control unit 80 includes a driving force demand block 81, a request arbitration block 82, a target calculation block 83, a torque capacity calculation block 84, and an implementation block 85, as shown in FIG.

The driving force demand block 81 calculates the target driving force Fd ^* based on the accelerator opening APO and the vehicle speed VSP, and converts the target driving force Fd ^* into the target engine speed Ne ^* using the engine overall performance characteristics. The profile of the target engine speed Ne ^* is calculated. When the lockup clutch 20 is completely released, the engagement request flag is output when the profile of the target engine speed Ne ^* is realized by the clutch slip control. On the other hand, when the lock-up clutch 20 is completely engaged, a release request flag is output when a profile of the target engine speed Ne ^* is realized by clutch slip control.

The request arbitration block 82 receives the engagement request flag and the release request flag from the driving force demand block 81, calculates a lockup request from various requests, and arbitrates the request to determine the priority. Various requirements include basic requirements, DP requirements (DP stands for Driving pleasure), drivability requirements, protection requirements, FS requirements (FS stands for Fail Safe), technical limit requirements, other system requirements, coast slip requirements, Etc.

The target calculation block 83 inputs the immediate release request flag, the release request flag, the slip request flag, and the engagement request flag from the request arbitration block 82, and calculates the target differential rotation speed ΔN ^* as a differential rotation target from these LU requests. . When the target differential rotation target or the release differential rotation target is calculated in the target calculation block 83, the target engine speed Ne ^* calculated by the driving force demand block 81 is input. A preset target slip characteristic is used for the immediate release differential rotation target and the slip differential rotation target.

The torque capacity calculation block 84 inputs the target differential rotation speed ΔN ^* , the prefetch turbine rotation speed Ntpre, the actual engine rotation speed Ne, and the like from the target calculation block 83. Then, the command torque (target LU torque Tlu ^* ) for realizing the target differential rotation speed ΔN ^* is calculated by calculating the corrected engine torque Tadj and the converter torque Tcnv (F / F control + F / B control).

The realization block 85 receives the target LU torque Tlu ^* from the torque capacity calculation block 84, converts the target lockup torque Tlu ^* into the lockup hydraulic pressure Plu, and further converts the lockup hydraulic pressure Plu into the command current Alu.

Here, in the coast slip control of the embodiment, as shown in FIG. 4, each function of the coast capacity learning control arranged in the realization block 85 is changed to a request arbitration block 82, a target calculation block 83, and a torque capacity calculation block 84. And rearranged. That is, the coast slip request function is arranged in the request arbitration block 82. In the target calculation block 83, a function for setting a target differential rotation speed ΔN ^* (= Nt−Ne), which is a target slip rotation speed in coast slip control, is arranged. The torque capacity calculation block 84 is provided with a torque capacity control function of the lockup clutch 20 based on the target differential rotation speed ΔN ^* in the coast slip control. However, when there is a coast slip request, the previous converter torque F / B compensation calculation value Tcnv_fb (c) is reset to the initial value.

[Detailed configuration of torque capacity calculation block, etc.]
FIG. 5 shows a target calculation block 83, a torque capacity calculation block 84, and a realization block 85 that constitute the lockup control unit 80. The detailed configuration of each of the

blocks

83, 84, and 85 will be described below with reference to FIG.

The target calculation block 83 includes a pre-read turbine rotational speed calculator 83a and a first subtractor 83b.

The prefetch turbine rotational speed calculator 83a inputs the prefetch speed ratio of the variator 4 and the secondary rotational speed Nsec from the secondary rotational sensor 97, and calculates the prefetch turbine rotational speed Ntpre that compensates for the hydraulic response delay in the lockup hydraulic control. To do. Note that the look-ahead gear ratio of the variator 4 is a gear ratio that is estimated to be reached when the hydraulic response delay time elapses, using the gear ratio, the speed ratio progress speed, and the hydraulic response delay time at that time.

The first subtractor 83b calculates the target differential rotation speed ΔN ^{* based} on the difference between the target engine speed Ne ^* calculated by the driving force demand block 81 and the prefetch turbine speed Ntpre calculated by the prefetch turbine speed calculator 83a. To do.

The torque capacity calculation block 84 has a look-ahead engine torque calculator 84a, a first adder 84b, a pump load torque calculator 84c, and a second differentiator 84d in the corrected engine torque calculation area 841.

The look-ahead engine torque calculator 84a receives the accelerator opening APO and the actual engine speed Ne, and uses a total engine performance map to estimate the look-ahead engine torque estimated to vary from the current engine torque to the hydraulic response delay time. ΔTepre is calculated. The current engine torque is acquired from the current accelerator opening APO, the actual engine speed Ne, and the engine overall performance map. The engine torque ΔTepre for the look-ahead is calculated by using the change rate of the accelerator opening APO and the actual engine speed Ne and the hydraulic response delay time, and the change width (positive or negative) of the engine torque from the current time until the hydraulic response delay time elapses. To do.

The first adder 84b calculates the pre-read engine torque Tepre by adding the actual engine torque Te acquired from the engine control unit 9 and the pre-read engine torque ΔTepre from the pre-read engine torque calculator 84a.

The pump load torque calculator 84c calculates a pump load torque Top that is a load torque by the oil pump 70 when being rotated by the engine 1.

The second subtractor 84d calculates a corrected engine torque Tadj (= Tepre-Top) based on the difference between the pre-read engine torque Tepre calculated by the first adder 84b and the pump load torque Top calculated by the pump load torque calculator 84c. To do.

The torque capacity calculation block 84 includes an F / F compensator 84e, a third difference unit 84f, a fourth difference unit 84g, an F / B compensator 84h, a minimum value selector 84i, and a second adder 84j. In the converter torque calculation area 842.

The F / F compensator 84e receives the target differential rotational speed ΔN ^* (= target slip rotational speed) from the first differentiator 83b, and calculates the converter torque F / F compensation Tcnv_ff corresponding to the target differential rotational speed ΔN ^*. calculate.

The third subtractor 84f inputs the actual engine rotational speed Ne from the engine rotational sensor 12 and the prefetch turbine rotational speed Ntpre calculated by the prefetch turbine rotational speed calculator 83a. Then, the actual differential speed ΔN is calculated from the difference between the actual engine speed Ne and the look-ahead turbine speed Ntpre.

The fourth subtractor 84g receives the target differential rotation speed ΔN ^* (= target slip rotation speed) from the first subtractor 83b and the actual differential rotation speed ΔN (= actual slip rotation speed) from the third subtractor 84f. To do. Then, a differential rotational speed deviation δ is calculated from the difference between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN.

The F / B compensator 84h receives the difference rotational speed deviation δ from the fourth differentiator 84g and performs PI feedback control on the converter torque F / B compensation calculated value Tcnv_fb (c) corresponding to the differential rotational speed deviation δ. (P: proportional, I: integral). The F / B compensator 84h, when there is a coast slip request due to establishment of the coast slip control start condition in the request arbitration block 82, sets the converter torque F / B compensation calculated value Tcnv_fb (c) up to the previous time as an initial value. Reset to.

The minimum value selector 84i inputs the converter torque F / B compensation calculated value Tcnv_fb (c) from the F / B compensator 84h and the upper limit torque value Tcnv_max for the converter torque F / B compensation. Then, the converter torque F / B compensation Tcnv_fb is output by selecting the minimum value.

Here, the upper limit torque value Tcnv_max for the converter torque F / B compensation is
Tcnv_max = Tadj−Tcnv_ff−K (K: fixed value)… (1)
(1), that is, a variable torque value corresponding to the corrected engine torque Tadj and the converter torque F / F compensation Tcnv_ff. Note that the fixed value K is set to be the upper limit torque value Tcnv_max that promotes the increase of the target LU torque Tlu ^* in the slip engagement scene of the lockup clutch 20. However, if the fixed value K is set to a torque value that is too low, the corrected engine torque Tadj that is the input torque to the torque converter 2 may not be exceeded due to the sum of the converter torque F / F compensation Tcnv_ff and the fixed value K. . That is, the target LU torque Tlu ^* does not become zero during the slip release scene of the lockup clutch 20, and the lockup clutch 20 cannot be released. Therefore, the fixed value K is a torque value that can exceed the corrected engine torque Tadj, which is the input torque to the torque converter 2, by considering the slip release scene of the lockup clutch 20 and the sum of the fixed value K and the converter torque F / F compensation. Set to the minimum value.

The second adder 84j adds the converter torque F / F compensation Tcnv_ff from the F / F compensator 84e and the converter torque F / B compensation Tcnv_fb from the minimum value selector 84i to calculate the converter torque Tcnv.

The torque capacity calculation block 84 includes a fifth differentiator 84k outside the corrected engine torque calculation area 841 and the converter torque calculation area 842. The fifth subtractor 84k calculates the target LU torque Tlu ^* by subtracting the corrected engine torque Tadj from the second subtractor 84d and the converter torque Tcnv from the second adder 84j.

The realization block 85 includes a torque → hydraulic converter 85a and a hydraulic → current converter 85b. The torque → hydraulic pressure converter 85a converts the target LU torque Tlu ^* input from the torque capacity calculation block 84 into the LU hydraulic pressure Plu. The hydraulic pressure → current converter 85b converts the LU hydraulic pressure Plu input from the torque → hydraulic converter 85a into an instruction current Alu.

[Coast slip control processing configuration]
FIG. 6 shows the flow of the coast slip control process executed by the lockup control unit 80 of the CVT control unit 8 of the embodiment. Hereinafter, each step of FIG. 6 showing the coast slip control processing configuration of the embodiment will be described. This process is repeatedly performed in a predetermined control cycle.

In step S01, following the start, it is determined whether a coast slip control start condition is satisfied. If YES (coast slip control start condition is satisfied), the process proceeds to step S02. If NO (coast slip control start condition is not satisfied), the process proceeds to the end.

Here, the coast slip control start condition is determined to be satisfied when a predetermined time has elapsed from the start of the fuel cut control after the accelerator release operation condition is satisfied during traveling and then the fuel cut control of the engine 1 is started. . The coast slip control start condition is added with an oil temperature condition that the shift hydraulic fluid temperature is equal to or higher than a predetermined temperature.

In step S02, following the determination that the coast slip control start condition is satisfied in step S01, the converter torque (FB) is reset, and the process proceeds to step S03.

Here, resetting the converter torque (FB) means resetting the converter torque F / B compensation calculated value Tcnv_fb (c) calculated so far by the torque capacity control process to the initial value.

In step S03, the torque capacity control (FIG. 7) of the lockup clutch 20 is executed following the resetting of the converter torque (FB) in step S02 or the determination that the coast slip control termination condition is not satisfied in step S04. Then, the process proceeds to step S04.

In step S04, following the LU clutch torque capacity control in step S03, it is determined whether a coast slip control end condition is satisfied. If YES (coast slip control end condition is satisfied), the process proceeds to the end. If NO (coast slip control end condition is not satisfied), the process returns to step S03.

[Lock-up clutch torque capacity control processing configuration]
FIG. 7 shows a flow of lockup clutch torque capacity control processing executed by the lockup control unit 80 of the CVT control unit 8 of the embodiment. Hereinafter, each step of FIG. 7 showing the lockup clutch torque capacity control processing configuration of the embodiment will be described. This process is repeatedly performed in a predetermined control cycle.

In step S1, following the start, the pre-reading turbine rotational speed Ntpre is calculated, and the process proceeds to step S2.

Here, the look-ahead turbine speed Ntpre is the turbine speed that compensates for the hydraulic response delay in the lock-up hydraulic control. The prefetch turbine rotational speed Ntpre is calculated in the prefetch turbine rotational speed calculator 83 a based on the prefetch speed ratio of the variator 4 and the secondary rotational speed Nsec from the secondary rotation sensor 97.

In step S2, following the calculation of the pre-reading turbine rotational speed Ntpre in step S1, a pre-reading engine torque Tepre is calculated, and the process proceeds to step S3.

Here, the look-ahead engine torque Tepre is an engine torque that compensates for the hydraulic response delay in the lockup hydraulic control. The pre-read engine torque Tepre is calculated by adding the actual engine torque Te acquired from the engine control unit 9 and the pre-read engine torque ΔTepre in the pre-read engine torque calculator 84a and the first adder 84b.

In step S3, following the calculation of the pre-reading engine torque Tepre in step S2, a corrected engine torque Tadj is calculated, and the process proceeds to step S4.

Here, the corrected engine torque Tadj is an engine torque input to the torque converter 2. The corrected engine torque Tadj is calculated in the second subtractor 84d by the difference between the pre-read engine torque Tepre and the pump load torque Top.

In step S4, subsequent to the calculation of the correction engine torque Tadj in step S3, based on the target rotational speed difference .DELTA.N ^*, calculates the converter torque F / F compensation min Tcnv_ff in accordance with the target rotational speed difference .DELTA.N ^*, step S5 Proceed to

Here, the “target differential rotational speed ΔN ^* ” is the target differential rotational speed ΔN ^* (= Nt−Ne: for example, a minute slip amount of about 200 rpm when the coast slip request is made. ) Is selected. In the case of a slip request in which the target slip rotation speed is not given, the first difference unit 83b calculates the difference between the target engine rotation speed Ne ^* and the pre-read turbine rotation speed Ntpre. The converter torque F / F compensation Tcnv_ff is the F / F of the lockup torque that converges to the target differential rotational speed ΔN ^* in the F / F compensator 84e that inputs the target differential rotational speed ΔN ^* (= target slip rotational speed). Calculated as compensation.

In step S5, following the calculation of the converter torque F / F compensation amount Tcnv_ff in step S4, the converter torque F / B compensation calculated value Tcnv_fb (c ) And the process proceeds to step S6.

Here, the “differential rotational speed deviation δ” is the difference between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN (= turbine rotational speed Nt−engine rotational speed Ne) in coast slip control in the case of coast slip request. Calculated. Then, the converter torque F / B compensation calculated value Tcnv_fb (c) is reset to the initial value by the converter torque F / B compensation calculated value Tcnv_fb (c) in the F / B compensator 84h. Is started as a converter torque F / B compensation amount that matches the target rotational speed ΔN ^* .

The “differential rotational speed deviation δ” is a slip request in which the target slip rotational speed is not given, and in the fourth subtractor 84g, the target differential rotational speed ΔN ^* from the first subtractor 83b and the third subtractor 84f. Is calculated by the difference between the actual rotational speed ΔN (= engine rotational speed Ne−pre-reading turbine rotational speed Ntpre). The converter torque F / B compensation calculated value Tcnv_fb (c) is calculated by the F / B compensator 84h as the converter torque F / B compensation for causing the actual differential rotational speed ΔN to coincide with the target differential rotational speed ΔN ^* .

In step S6, following the calculation of converter torque F / B compensation calculation value Tcnv_fb (c) in step S5, converter torque F / B compensation calculation value Tcnv_fb (c) is the upper limit of converter torque F / B compensation. It is determined whether the torque value is equal to or less than Tcnv_max. If YES (Tcnv_fb (c) ≦ Tcnv_max), the process proceeds to step S7. If NO (Tcnv_fb (c)> Tcnv_max), the process proceeds to step S8.

In step S7, following the determination that Tcnv_fb (c) ≦ Tcnv_max in step S6, the converter torque F / B compensation amount Tcnv_fb is set as the converter torque F / B compensation calculated value Tcnv_fb (c), and the process proceeds to step S9. move on.

In step S8, following the determination that Tcnv_fb (c)> Tcnv_max in step S6, the converter torque F / B compensation amount Tcnv_fb is set as the upper limit torque value Tcnv_max for the converter torque F / B compensation, and the process proceeds to step S9. .

Here, the selection of the converter torque F / B compensation Tcnv_fb in steps S6 to S8 is performed in the minimum value selector 84i.

In step S9, following the setting of the converter torque F / B compensation Tcnv_fb in step S7 or step S8, the converter torque Tcnv is calculated, and the process proceeds to step S10.

Here, the converter torque Tcnv is calculated by adding the converter torque F / F compensation Tcnv_ff from the F / F compensator 84e and the converter torque F / B compensation Tcnv_fb from the minimum value selector 84i.

In step S10, following calculation of converter torque Tcnv in step S9, target LU torque Tlu ^* is calculated, and the process proceeds to step S11.

Here, the target LU torque Tlu ^* is calculated by subtracting the corrected engine torque Tadj calculated in step S3 and the converter torque Tcnv calculated in step S9 in the fifth differentiator 84k.

In step S11, following the calculation of the target LU torque Tlu ^* in step S10, the torque LU pressure converter 85a converts the target LU torque Tlu ^* into the LU oil pressure Plu, and the process proceeds to step S12.

In step S12, following the conversion to the LU hydraulic pressure Plu in step S11, the hydraulic pressure → current converter 85b converts the LU hydraulic pressure Plu to the command current Alu, and the process proceeds to step S13.

In step S13, following the conversion to the instruction current Alu in step S12, the instruction current Alu is output to the lockup pressure solenoid valve 76, and the process proceeds to the end.

Next, the operation of the embodiment is divided into “coast slip control and its problems in the comparative example”, “replacement study of coast capacity learning control and coast slip control”, and “coast slip control operation in the embodiment”. explain.

[Coast capacity learning control and its problem in comparative example]
FIG. 8 is a time chart showing coast capacity learning control executed during coasting in the comparative example. The coast capacity learning control and its problem in the comparative example will be described below with reference to FIG. In the comparative example, during coast running, coast capacity learning control of the lock-up clutch arranged in the realization block is executed.

In the case of this comparative example, when the accelerator release operation is performed at time t1 in FIG. 8 and the idle switch is turned on in the LU clutch engaged state, deceleration starts, and engine torque Te, engine speed Ne, turbine speed Nt begins to decline. Then, when the engine torque Te is switched from positive to negative at time t2, the decreasing gradients of the engine torque Te, the engine speed Ne, and the turbine speed Nt become gentler than before time t2.

When the fuel cut flag is set at time t3 and the fuel supply of the engine is stopped, the previous learning value is set as the initial value of the LU command differential pressure, the coast capacity learning condition is satisfied, and the learning start set is set. The target slip rotation F / B control is started at time t4 when the turbine rotation speed Nt is reduced to the threshold value due to the increase in the volume of the LU command differential pressure by the F / F control from time t3.

At time t5, when the actual slip rotation speed between the turbine rotation speed Nt and the engine rotation speed Ne falls below the threshold value, the convergence learning control to the target slip rotation speed is started. Then, at time t6 when the actual slip rotation speed is equal to or less than the threshold value and the slip convergence condition that the predetermined time elapses is satisfied, the convergence learning control is terminated, and the LU instruction differential pressure at time t6 is used as a learning value to be used next time Is updated.

From time t6 to accelerator re-depressing operation time t7, by retaining the LU command differential pressure at time t6, the actual slip rotation speed between the turbine rotation speed Nt and the engine rotation speed Ne is a minute difference rotation speed ΔN Μ slip control is performed to maintain the. Note that the slip differential rotation in the coast state becomes an input from the drive wheel side, so that the turbine rotational speed Nt> the engine rotational speed Ne is in a relationship opposite to the drive state (Ne> Nt).

As described above, in the comparative example, the coast capacity learning control is repeatedly experienced until a desired learning value can be acquired as the initial value of the LU instruction differential pressure when starting the coast capacity learning control. There is a need. Also, the LU instruction differential pressure learning value by learning is used as the initial value at the start of coast capacity learning control. For this reason, the initial differential pressure varies depending on the operating state before the coast capacity learning control is started, and the slip amount varies in the start area of the coast capacity learning control (the target slip rotation F / B control area or the like).

[Consideration of coast capacity learning control and coast slip control]
The reason why the coast capacity learning control of the comparative example is arranged in the realization block will be described.
When switching from the drive state to the coast state, if the lockup capacity is excessive, a shock to enter the fuel cut occurs. On the contrary, if the lockup capacity is insufficient, the engine speed is increased. Therefore, there is a demand to reduce the lock-up capacity at the time of coasting to a marginal capacity corresponding to the coast torque so that there is no excess or deficiency in capacity.

As described above, the lockup capacity corresponding to the coast torque is a physical quantity unique to the hardware, and therefore, the learning control is based on the coast driving experience. Since learning control needs to detect a physical quantity, the coast capacity learning function is arranged in a realization block (hardware specific function).

Next, it will be examined based on the flowchart of FIG. 9 whether the coast capacity learning control arranged in the realization block can be replaced with the coast slip control in the form of various modes of slip control. The idea is as follows.

StepA verifies whether the requirements for coast slip control and coast capacity learning control are the same. The reason is that if the function of the same request is implemented, it can do what it wants.

In Step B, if the request is the same, verify whether the mechanism (solution principle) of both controls is the same. The reason is that the same requirements can be satisfied if the solution principle is the same.

In StepC, if the requirements and principles are the same, we will examine whether this function can ensure the same performance as coast capacity learning. The reason is that if the principle is really the same, the control result should be the same.

In StepD, if the requirements and principles are the same, and equivalent performance can be secured or there is a prospect of achievement, the function can be replaced.

In StepE, if the requirements for coast slip control and coast capacity learning are different, the principle is different, or equivalent performance can be secured or there is no prospect of achieving it, the function cannot be replaced.

It is verified whether the coast slip control and the coast capacity learning control of Step A are the same. The basic requirements are the same in that you want to perform a coast slip (to keep the LU capacity at the bare limit) to improve engine stall resistance, prevent deceleration from being pulled in, and lower the LU release vehicle speed. That is, in a sudden braking scene on a low μ road, which is a typical scene, there is a demand to release the LU clutch with good response to prevent engine stall. The condition for entering control and the condition for missing control are the same even if the coast capacity learning control is transferred to the coast slip control. In addition, since slip control can be performed by target differential rotation in torque capacity calculation, coast slip control should be able to perform the same as coast capacity learning control.
From the above verification, it was confirmed that the requirements were the same for the coast slip control and the coast capacity learning control.

Verify whether the principles of Coast slip control and coast capacity learning control in Step B are the same. The mechanism of both controls is to make a differential pressure value that can stably maintain a minute slip rotation. On the other hand, the F / B control in the torque capacity calculation block 84 in the coast slip control after the LU reconstruction is to control the hydraulic pressure so as to maintain the differential rotation, and has the same principle as the coast capacity learning control. .
From the above verification, it was confirmed that the principles of coast slip control and coast capacity learning control are the same.

It is verified whether the coast slip control of StepC can secure the same performance as the coast capacity learning control. For this, it was confirmed from the experimental data of the single-plate LU clutch that coast slip control itself was possible and that release responsiveness in coast slip control during sudden deceleration (0.6G deceleration) could be secured. It was done. And since it is a multi-plate LU clutch, coast slip control is not impossible.
From the above verification, it was confirmed from the experimental data that there is a possibility of achieving the same performance as the coast capacity learning control performance by the coast slip control.

This verification method proceeds from Step A → Step B → Step C → Step D in the flowchart of FIG. 9 and obtained a verification result that coast capacity learning control can be replaced with coast slip control.

[Coast slip control action in the embodiment]
Based on the above verification results, the present inventors reset the converter torque F / B compensation to the initial value and perform coast slip control when the coast slip control start condition is satisfied during coast travel by the accelerator release operation. Adopted means to start. More specifically, each function of the coast capacity learning control arranged in the realization block 85 is rearranged in the request arbitration block 82, the target calculation block 83, and the torque capacity calculation block 84, and the coast capacity learning control is coasted. The configuration is replaced with slip control.

As described above, when the start condition is satisfied by rearranging the functions of the coast capacity learning control that has been arranged in the realization block 85, the initial value for the converter torque F / B compensation is reset and the coast slip control is performed. Be started. As a result, it is possible to maintain a stable slip rotation immediately after the start of the coast slip control without performing learning control during coasting.

The operation of the coast slip control process will be described based on the flowchart shown in FIG.
When the coast slip control start condition is satisfied, the process proceeds from S01 → S02 → S03 → S04, and while the coast slip control end condition is not satisfied, the process proceeds from S03 to S04 is repeated.

In step S02, the converter torque F / B compensation calculated value Tcnv_fb (c) calculated up to the previous time by the torque capacity control process is reset to the initial value. That is, the converter torque F / B compensation calculated value Tcnv_fb (c) including the integral term is reset and the coast slip control is started.

In step S03, torque capacity control (FIG. 7) of the lockup clutch 20 in coast slip control is executed. In the torque capacity control of the lockup clutch 20, the target differential rotational speed ΔN ^* (= Nt−Ne), which is the target slip rotational speed for coast slip control, is selected as “target differential rotational speed ΔN ^* ” in step S4. Is done. In step S5, the “differential rotational speed deviation δ” is calculated from the difference between the target differential rotational speed ΔN ^* and the actual differential rotational speed ΔN (= turbine rotational speed Nt−engine rotational speed Ne) in coast slip control. Then, in the F / B compensator 84h, the converter torque F / B compensation calculation value Tcnv_fb (c) is calculated as the converter torque F / B compensation for making the actual differential rotation speed ΔN coincide with the target differential rotation speed ΔN ^*. The

Thereafter, when the coast slip control end condition of step S04 is satisfied, the process proceeds to the end, and the coast slip control is ended.

Next, the coast slip control action executed during the coast running in the embodiment will be described based on the time chart shown in FIG.

In the case of this embodiment, in the LU clutch engaged state, when the accelerator release operation is performed at time t1 in FIG. 10 and the idle switch is turned on, the deceleration starts, and the engine torque Te, the engine speed Ne, and the turbine speed Nt begins to decline. Then, when the engine torque Te is switched from positive to negative at time t2, the decreasing gradients of the engine torque Te, the engine speed Ne, and the turbine speed Nt become gentler than before time t2.

When the fuel cut flag is set at time t3 and a predetermined waiting time has elapsed when the engine torque from time t3 to time t4 approaches the fuel stop torque, coast slip control is started at time t4. That is, a coast slip request is output at time t4, the target differential rotation speed in coast slip control is set, and the LU torque is slightly increased by increasing the volume of the LU command differential pressure by F / F control.

A section from time t4 to time t5 until the coast slip end condition is satisfied is a coast slip control section. In this coast slip control section, the capacity of the LU command differential pressure is controlled by F / F compensation and F / B compensation for converging the actual differential rotational speed ΔN to the target differential rotational speed ΔN ^* in the coast slip control.

Due to this LU commanded differential pressure capacity control, there is no need to perform learning control, and immediately after the start of coast slip control, the differential rotational speed ΔN due to the minute slip amount between the turbine rotational speed Nt and the engine rotational speed Ne is stably maintained. Will be.

As described above, in the lock-up control device of the belt type continuously variable transmission CVT of the embodiment, the effects listed below can be obtained.

(1) The torque converter 2, the lockup clutch 20, and the transmission controller (CVT control unit 8) are provided.
The torque converter 2 is interposed between the travel drive source (engine 1) and the speed change mechanism (variator 4).
The lock-up clutch 20 is provided in the torque converter 2 and directly connects the torque converter input shaft and the torque converter output shaft by fastening.
The transmission controller (CVT control unit 8) controls the engagement / slip / release of the lock-up clutch 20.
The transmission controller (CVT control unit 8) calculates the converter torque Tcnv by feedforward compensation based on the target differential rotational speed ΔN ^* and feedback compensation based on the differential rotational speed deviation δ, and the input torque (correction engine) to the torque converter 2 is calculated. A lockup control unit 80 is provided that performs slip control to obtain a target lockup torque Tlu ^* calculated by subtracting the converter torque Tcnv from the torque Tadj).
The lockup control unit 80 resets the converter torque F / B compensation in the feedback compensation to the initial value and starts the coast slip control when the start condition of the coast slip control is satisfied during the coast traveling by the accelerator release operation. .
In this way, by starting the coast slip control by resetting the initial value for the converter torque F / B compensation, it is not necessary to perform learning control during coast driving, and stable slip rotation is maintained immediately after the start of coast slip control. be able to. In other words, by resetting the initial value for the converter torque F / B compensation, at the start of the coast slip control, the influence on the coast slip control due to the torque value for the converter torque F / B compensation by the previous integral term is eliminated. .

(2) The driving source for traveling is the engine 1.
The lockup control unit 80 starts the fuel cut control of the engine 1 after the accelerator foot release operation condition is satisfied during traveling, and the coast slip control start condition is satisfied when a predetermined time elapses from the start of the fuel cut control. Suppose that
Thus, by adding a time condition to the start condition of coast slip control and waiting for the engine torque to stabilize, coast slip control that converges to an appropriate slip amount with good response immediately after the start of control can be executed. .

(3) When the coast slip control start condition is satisfied, the lockup control unit 80 sets the target differential rotation speed ΔN ^* due to a small slip rotation of a constant value, and calculates the converter torque F / B compensation calculated value Tcnv_fb up to the previous time. (c) is reset to the initial value.
As described above, when the coast slip control is started by setting the target differential rotation speed ΔN ^* and resetting the initial value when the control start condition is satisfied, the slip of the lock-up clutch 20 is made early as in the coast capacity learning control. Can be controlled.

(4) The lockup control unit 80 includes a request arbitration block 82, a target calculation block 83, a torque capacity calculation block 84, and an implementation block 85.
The functions of the coast capacity learning control that have been arranged in the realization block 85 are rearranged in the request arbitration block 82, the target calculation block 83, and the torque capacity calculation block 84.
In this way, by relocating each function of the coast capacity learning control that has been arranged in the realization block 85, the lockup control unit 80 can change the coast lockup control without changing the basic configuration of the lockup control unit 80. Can be incorporated.

The automatic transmission lockup control device of the present invention has been described above based on the embodiments. However, the specific configuration is not limited to the first embodiment, and design changes and additions are allowed without departing from the spirit of the invention according to each claim of the claims.

In the embodiment, an example in which the lockup control unit 80 includes the drive force demand block 81 that converts the target drive force Fd ^* into the target engine speed Ne ^* is shown. However, the lock-up control unit may not be provided with a driving force demand block, and may be an example in which slip control is performed by giving a target slip rotation speed characteristic.

In the embodiment, an example in which the lockup control device of the present invention is applied to an engine vehicle equipped with a belt type continuously variable transmission CVT as an automatic transmission is shown. However, the lock-up control device of the present invention may be applied to a vehicle equipped with a stepped transmission called step AT or a vehicle equipped with a continuously variable transmission with a sub-transmission as an automatic transmission. Further, the applied vehicle is not limited to an engine vehicle, and can be applied to a hybrid vehicle in which an engine and a motor are mounted on a traveling drive source, an electric vehicle in which a motor is mounted on a traveling drive source, and the like.

Claims

A torque converter interposed between the traveling drive source and the speed change mechanism;
A lock-up clutch that is provided in the torque converter and that directly connects the torque converter input shaft and the torque converter output shaft by fastening;
A transmission controller that controls engagement / slip / release of the lock-up clutch, and
A target lock is calculated by calculating a converter torque by feedforward compensation based on a target differential rotational speed and feedback compensation based on a differential rotational speed deviation in the transmission controller, and subtracting the converter torque from an input torque to the torque converter. Provide a lock-up control unit that performs slip control to obtain up torque,
The lockup control unit resets the converter torque feedback compensation amount in the feedback compensation to the initial value and starts the coast slip control when the coast slip control start condition is satisfied during the coast running by the accelerator release operation.
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to claim 1,
The driving source for traveling is an engine;
The lockup control unit starts the fuel cut control of the engine after the accelerator release operation condition is established during traveling, and when a predetermined time elapses from the start of the fuel cut control, the start condition of the coast slip control is Suppose that
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to claim 1 or 2,
When the start condition of the coast slip control is satisfied, the lockup control unit sets a target differential rotation speed by a minute slip rotation of a constant value, and resets a converter torque feedback compensation calculation value up to the previous value to an initial value.
Automatic transmission lockup control device.
In the automatic transmission lockup control device according to any one of claims 1 to 3,
The lockup control unit
A request arbitration block that arbitrates various requests and determines priorities;
A target calculation block that inputs a request flag from the request arbitration block and calculates a target differential rotation speed that is a differential rotation target;
A torque capacity calculation block for inputting a target differential rotation speed from the target calculation block and calculating a target lockup torque for realizing the target differential rotation speed;
A realization block for converting a target lockup torque from the torque capacity calculation block into a lockup hydraulic pressure instruction value;
Relocating each function of coast capacity learning control that has been arranged in the realization block to the request arbitration block, the target calculation block, and the torque capacity calculation block,
Automatic transmission lockup control device.
A lockup control method for an automatic transmission, comprising: a torque converter interposed between a driving source for traveling and a transmission mechanism; and a lockup clutch that directly connects a torque converter input shaft and a torque converter output shaft by fastening. There,
When requesting slip engagement of the lock-up clutch,
Calculate the converter torque feed forward compensation based on the target differential speed,
Calculate the converter torque feedback compensation based on the differential speed deviation,
The converter torque is calculated from the converter torque feedback compensation and the converter torque feedback compensation,
Calculate the input torque to the torque converter,
Subtracting the converter torque from the input torque to calculate a target lockup torque,
According to this target lockup torque, the lockup hydraulic pressure is supplied,
Here, during coast running by accelerator release operation, when the start condition of coast slip control is satisfied, the converter torque feedback compensation is reset to an initial value, and coast slip control is started.
Automatic transmission lockup control method.